Thank you so much for your reassurance!! This forum seems to be half and half with people that are sure any little touch will kill a chick, and others who seem more confident in chicks' ability to survive if they are strong enough. I really appreciate your response! I think I'm panicking myself and you gave me a much needed reality check. I will update on the status of the chicks - right now I keep going to check on them and their responses but I want to let them sleep for now. I've never read about any hairline crack pips but that gives me hope. I like the words 'all is well' though!Your eggs are probably right on time. If temps are just a little low, they can be a couple days late. If the eggs are responding to sound, then all is well. They should start pipping soon. Often you can't see the tiny pips. It may only be a tiny hairline scratch on the surface that can only be seen when light shines from just the right angle..... or the pip could be positioned away from your viewing window and impossible to see. If you "hear" your eggs peeping, then you know they're pipped &/or zipping.
Also, after an egg pips, the chicks rests for a very long time. Mine can wait 12-24 hrs before they start zipping, so when I spot the 1st pip, I know that chicks are coming in the next day. Although I saw 3 pips this morning, I still have no chicks. I might have a chick or 2 tonight, but it looks like tomorrow morning will be the big excitement. (i'm up to 5 pips now, and someone is peeping.)
Good luck for your hatch, and happy birthday!